Worldwide interest in converting phytoplankton into biofuels and bioproducts has grown to an unprecedented level over the last decade. An untold number of companies and organizations are now actively engaged in developing and commercializing a variety of pathways to make sensible use of this highly renewable and seemingly limitless resource. During 2009 and 2010, the US Department of Energy has provided a significant amount of financial support for programs in this field, and that in turn has spurred the inflow of hundreds of millions of dollars in venture and investment banking capital.
Most of the excitement about phytoplankton has to do with its exceptionally high and bountiful per unit area yield of lipids—5,000 to 20,000 US gallons per acre per year—7 to 30 times greater than the next best agricultural crop. More than 300,000 types of phytoplankton have been identified, and the lipid content can range from 5 wt % to 60 wt % by weight. In addition to the lipids, phytoplankton also contain carbohydrates and protein, compounds that can also be converted into additional biofuels and bioproducts, and/or food for human and animal consumption. FIG. 1 illustrates the distribution of lipids, carbohydrates and protein in a typical class of phytoplankton.
Phytoplankton in general have the approximate formula C108H180O45N16S. Because their carbon is derived from CO2, their nitrogen from NH4+, most of their hydrogen from water, and most of their oxygen they evolve comes from CO2. We may write the following stoichiometric formula for the using of phytoplankton to provide photosynthetic carbon fixation:
 ComponentsMolar RatioWt. RatioO2/Phytoplankton1181.5534CO2/Phytoplankton1061.9192O2/CO21.11320.8094
TABLE 1CHEMICAL COMPOSITION (WT % DRY BASIS)OF PHYTOPLANKTONWt % (Dry)ComponentsCarbohydrates40Protein30Lipids30Total100Chemical AnalysisC52.3782H7.4636O29.6194N9.2197S1.3191TOTAL100.0000
The net effort is that when one mole of phytoplankton is produced, 106 moles of CO2 are removed from the air and meanwhile 118 moles of O2 are released to the atmosphere in the presence of an excess of water.
The above photosynthetic carbon fixation process has tremendous value when applied to industrial sources of CO2 emissions such as fossil fuel fired power generation, cement manufacturing, etc.
The above situation notwithstanding, almost every phytoplankton-based technology and process that is presently being developed has one thing in common, and that has to do with the need to extract the immobilized lipids at some intermediate stage. The universal focus of attention in this emerging industry has to do with the term “extraction,” as in the extraction of lipids.
Unfortunately, it has become increasingly apparent that the extraction of immobilized lipids from phytoplankton at a commercial scale is very expensive, both in terms of capital and operating costs, especially with respect to energy consumption. In a laboratory environment, when dealing with a few hundred pounds of phytoplankton feedstock, most lipid extraction methods look promising, albeit some more than others. However, simple extrapolation of these results without careful consideration to energy consumption can often be highly misleading. We have actually analyzed proposed processes in which the energy used to extract the lipids is greater than the energy value of the end product.
Significance of Our Invention
Our invention is unique insofar that the process is intended to “react” rather than “extract” the immobilized lipids. In a practical sense, we bypass the extraction step and directly convert the immobilized lipids contained in the phytoplankton slurry into fatty acids. We need almost no dewatering and absolutely no drying of the phytoplankton, thereby affecting significant savings in capital equipment and energy costs. Subsequently, since we do not extract the lipids, we save even more in terms of capital and energy.
End Product Applications
The fatty acids manufactured by our process can be used as a feedstock for making the following biofuels and bioproducts:                Biodiesel (methyl ester) by catalytic distillation of the fatty acids with methanol.        Biodiesel (ethyl ester) by catalytic distillation of the fatty acids with ethanol - suitable in countries such as Brazil with low cost ethanol supplies.        Biolubricants (higher alkyl esters) by catalytic distillation of the fatty acids with higher alcohols such as octanol.        Green diesel by catalytic hydroprocessing of the fatty acids.        Biojet fuels by 1) catalytic decarboxylation of the fatty acids to make paraffinic hydrocarbons, followed by 2) mild hydrocracking and hydroisomerization of the paraffinic hydrocarbons to C10-C15 branched paraffins (jet fuel).        Fatty alcohols by catalytic hydrogenation of the fatty acids.Valuable Byproduct        
After the immobilized lipids have been reacted to make fatty acids, and this fatty acid product has been separated, the deoiled phytoplankton biomass that remains is dried and processed for use as a high protein food for human or animal consumption.